Aluminum and its alloys have come increasingly into use for the fixed jaw bodies and movable jaws of spot-welding guns because of their weight being only about one-third of copper from which previous welding guns were commonly made. Aluminum, however, is easily attacked by corrosive agents present in contaminated water with the result that the aluminum oxide powder resulting from corrosion of the aluminum clogs the water cooling passageways and causes failure of the welding gun. Aluminum castings provided with nickel tubes seated therein which were previously tried were found to fail when corrosion of the aluminum took place so that the tubes filled up with aluminum oxide powder and the brass water fittings came out taking portions of aluminum with them. Aluminum surfaces exposed to air also corroded to a lesser extent, but sufficiently to prevent good electrical contact between the aluminum and the adjacent electrical current conductor connected thereto.